class Solution {
public:
    int mySqrt(int x) {
        if(x<1)
        return 0;
        int left=1,right=x;
        while(left<right)
        {
            long long mid=left+(right-left+1)/2;
            if(mid*mid<=x)
            left=mid;
            else 
            right=mid-1;
        }
        return left;
    }
};
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